I just had too many neighbours
Starting position way too hard to defend + some bad decisions. I could somehow secure border with Pan only, but it should have been better [but some bad luck in the beginning + bad pretender moves]. The problem was with Atlantis and Utgard. It's a bit bad luck to get anyone like Ylvali in MP game, but well, cost of newbie game. I couldn't concentrate enough forces to eradicate Agartha and also Agartha wass not pushed hard enough on other borders. I managed to practically kill Atlantis and kill most of Agarthan armies but my armies were spread too thin. No natural chokepoints. It could work really differently with a bit better starting position.